CoachLens 2.0 — Your On-Device AI Coach

Inspiration

The idea for CoachLens 2.0 came from noticing how students and professionals spend hours reading online content without truly understanding or remembering it. I wanted to make learning more active, engaging, and personalized. The release of Chrome’s built-in AI with Gemini Nano felt like the perfect moment to create a tool that turns any webpage into an interactive classroom while keeping everything private and fast.

What it does

CoachLens 2.0 transforms any webpage into a personalized AI-powered learning companion. It summarizes complex information, explains concepts with real-world examples, and generates interactive quizzes based on what you are reading. Users can also track their learning journey through a timeline and chat with an AI tutor that understands the full context of the page. The best part is that it runs locally with Gemini Nano, ensuring privacy and instant feedback even without an internet connection.

How we built it

I built CoachLens 2.0 as a Chrome Extension using JavaScript, HTML, and CSS with Manifest V3. The frontend manages page interactions, while a Node.js backend supports optional hybrid AI functionality.

~The Prompt API and Summarizer API handle dynamic understanding of webpage content. ~The Writer, Rewriter, and Proofreader APIs refine text explanations and user-generated responses. ~The Translator API adds multilingual capabilities for global learners. ~A hybrid AI engine automatically detects whether Gemini Nano is available locally and switches to the Gemini 2.5 Flash API for cloud processing when needed. ~I also implemented real-time progress tracking and quiz generation logic using structured prompts and local caching for fast responses.

Challenges we ran into

Building a seamless hybrid AI system was the biggest challenge. Ensuring smooth fallback between local and cloud models without lag took multiple iterations. Handling complex webpage structures and extracting meaningful content for summarization was also tricky. Another major hurdle was maintaining Chrome extension performance while running AI logic locally without slowing the browser.

Accomplishments that we're proud of

I am proud that CoachLens 2.0 can truly understand and teach from any webpage. It is one of the first Chrome extensions to combine on-device and cloud AI for an interactive learning experience. Seeing the AI explain concepts, generate quizzes, and summarize content in real time feels like unlocking a new way to learn online. It’s fast, private, and surprisingly fun to use.

What we learned

This project taught me how to design for both performance and privacy. I learned to integrate multiple Chrome AI APIs into a single flow and handle multimodal inputs effectively. More importantly, I learned that hybrid AI is the future, combining the privacy of local AI with the power of cloud AI creates the best possible experience for users.

What's next for CoachLens 2.0 — Your On-Device AI Coach

Next, I plan to bring voice interaction and speech-to-text capabilities so users can talk to their AI tutor directly. I also want to add collaboration features where friends or classmates can learn together through shared timelines and group quizzes. In the long run, the goal is to expand CoachLens into a full hybrid AI learning ecosystem that works across browsers and mobile devices.

Built With

• chrome-built-in-ai-(gemini-nano)
• chrome-extensions-api
• css3
• express.js
• google-gemini-2.5-flash-api
• google-generative-ai-sdk
• html5
• javascript
• manifest-v3
• node.js
• on-device-intelligence-google-gemini-2.5-flash-api-?-for-hybrid-fallback-and-advanced-processing-prompt-api-?-for-dynamic-content-understanding-summarizer-api-?-for-structured-page-summaries-writer-api
• prompt-api
• proofreader-api
• rewriter-api
• speech
• summarizer-api
• translator-api
• web
• writer-api